Question

10 ml of alkane on complete combustion gives 30 ml of Co, Find formula of alkane.​

Answer 1

I will reedit my ans...

Answer 2

Provided they are all gases then the formula is going to be

C4H10

they key here is that 1 mole of any ideal gass occupies the same volume as 1 mole of any other ideal gas under the same conditions of temperature and pressure. So, since the same volume of any ideal gas has the same number of moles then you can treat the ratio of volumes as the ratio of moles.

the ratio of volumes is

10 : 40 : 50

1 : 4 : 5

all the Carbon from the hydrocarbon is in the CO2

10 ml of hydrocarbon produces 40 ml CO2,

1 : 4 ratio

So 1 mole hydrocarbon has 4 moles Carbon

All the H ends up in the water

10 ml hydrocarbon produces 50 ml water,

1 : 5 ratio,

but also each water has 2 H atoms

So 1 mole hydrocarbon has 10 moles Hydrogen

which gives

C4H10